Reduced-oxygen display and storage, through the limitation of oxidative processes, can enhance the preservation of works on paper. By limiting photo-oxidative processes, access to objects can be increased, allowing their display at higher light levels and/or for longer periods. Published research indicates that most artists’ materials will either benefit from or suffer no detrimental effect from reduced-oxygen environments. However, some colourants have been found to undergo accelerated change in the absence of oxygen. Therefore, evaluation of benefits to heritage objects prior to reduced-oxygen treatment is required. The Anoxic Frames Project at Tate, of which this Thesis is an outcome, aimed to develop reduced-oxygen framing solutions, test their efficacy, identify materials that undergo accelerated change in a reducedoxygen environment and develop methods to identify candidate objects for anoxic storage. The scope of my research at Tate and for this Thesis was limited to 19th-century watercolour drawings, with a focus on J.M.W. Turner. My research contributed to several publications, conference papers, posters, reproduction of a 19th- century paper, a prototype reaction cell and was, in part, patented. This Thesis presents: a literature review of both the behaviour of artists’ materials in zero oxygen (anoxia) and of analytical methods; a technical study leading to the reproduction of a paper used by Turner; analytical studies of the photo-reactivity of madder lakes and Prussian blues; the design and testing of a prototype reaction cell for operando spectroscopy studies of heritage materials; an outline of the field of heritage degradomics; the application of heritage degradomics with advanced chemometric methods to evaluate the headspace profiles of watercolours aged in both anoxia and room atmosphere. The Thesis concludes with an evaluation of reduced-oxygen treatment, and a proposal of how heritage institutions can both select objects suitable for reduced-oxygen storage and display and implement low-cost reducedoxygen cassettes in their display practice.

The Modular System draws on traditional wood engraving, woodcut and letterpress practices. It comprises two printing surfaces and printing furniture specifically devised to facilitate offset and transfer relief printing. Rigid acetal resin tint blocks, hand or laser engraved, generate tone or colour that may be applied to more than one image. Multiple overprinting produces variant colour mixtures. Their function is similar to late nineteenth-century tints devised for colour letterpress printing. Compound printing surfaces of linoleum or vinyl are segmented and joined to make removable and replaceable parts. They print variable configurations in a process that resembles historical solutions to simultaneous colour printing: from the Mentz Psalter (1475), to the compound plates of William Congreve (1820) and the segmented wood engravings of John Holt Ibbetson (1819). These compound surfaces also act as receptors for impressions from the tint blocks. Repositioning and offsetting them is expedited by press furniture especially devised for the project. Registration devices are based on the simple Japanese kentō system and laser-cut circular chases derived from traditional letterpress furniture. Printing the tint blocks directly onto the flexible compound surfaces produce two viable prints that are offsets of each other. They are reversed, but one offset is also tonally inversed. It is this unpredictable tonality that has driven this experimental project. Both the construction and processes developed using the Modular System directed historical research into functional colour relief printing which consequently unearthed examples that would influence the further development of the project. This has generated both devices and processes capable of wider applications. Printing surfaces employed in the Modular System may be laser engraved or cut and adapted to use in both lithography and intaglio printmaking.

This thesis presents a novel approach for modelling complex papermaking systems via a combination of existing techniques. The project has addressed the question of modelling the process known as retention on production paper machines using a semiphysical method. This method combines both complicated physical analysis of key papermaking equipment and the use of neural networks to model the dynamic components and interactions that cannot be readily modelled via physical equations. This approach was adopted to satisfy the requirements of the sponsoring company, English China Clays International (ECCI), that the finished modelling methodology should be readily adaptable to different papermaking situations, as required. A semiphysical model was determined to meet all the criteria set by ECCI. The development of the semi physical modelling method is described through the stages of first application in a laboratory scale application (a pilot paper machine), to the final testing and validation of the technique on real data, gathered on industrial papermachines. Neural networks and their application to retention modelling are also described in this thesis, as their usage was employed in parts of the semiphysical model structure. Also, the concept of neural network error compensators are discussed. This is a novel application of a neural network to predict and then correct the modelling error of a system, thereby increasing the accuracy of the final result.

Although much academic research has been devoted to the fields of paper drying and air impingement heat transfer, little of the resulting information is in a form usable to dryer manufacturers. The aim of this research was therefore to develop a model suitable for the designing the flotation dryers often used in the production of market pulps. The heat transfer characteristics of several commercial nozzle designs, namely flotation nozzles, slot nozzles and arrays of round orifices, were determined under conditions relevant to pulp drying. Empirical correlations for the Nusselt number for the nozzles were obtained using the property ratio method to account for the variation of the physical properties of air with temperature. The proposed correlations were shown to be in excellent agreement with the experimental results and were sufficiently accurate for use in industrial dryer design. The effect of the nozzle exit velocity and nozzle-to-surface spacing on the profile of static pressure at the impingement surface was also determined for a typical flotation nozzle design. The influence of nozzle conditions and sheet properties on the drying characteristics of papermaking pulp was determined through batch drying experiments. Over 400 experiments were performed using samples produced from four furnishes at basis weights in the range 120 g/m" to 2125 g/m2 and oven dry densities in the range 175 kg/mt to 900 kg/m'. Drying was achieved using heated air emerging from flotation nozzles at air temperatures in the range 100°C to 250°C with nozzle velocities between 15 mls and 55 mls. Temperature profiles through handsheets of both pressed and unpressed pulp were also measured during drying, which showed the presence of a quasi-constant temperature.

It has long been known that waste newsprint can be deinked effectively only if a proportion of coated waste is added to it. Coated waste paper is not always in good supply, and can cost more than waste newsprint. The present research has thrown new light on why coated waste is required. In flotation deinking, two distinct processes act to separate ink from pulped stock. Firstly, air bubbles rising through the liquid phase collect ink particles and carry them to the surface. The ink particles are then retained by the foam on the surface until it is removed. The commercial deinking plant that was the subject of the present study uses a proprietary chemical, which is intended to act effectively in both processes. Chemical speciation has shown that the chemical species in the foam and in the bulk solution have similar thermodynamic properties. This implies that the chemical process operates independently of the presence of coated waste. Comparison of results gathered in full-scale and in pilot deinking equipment has shown that the foam is more stable when the waste paper being deinked contains coated waste. The key role of coated material is therefore to stabilise the foam, and so prevent re-mixing of ink with the deinked fibre slurry. These facts suggest that to achieve good deinking without having to use coated waste, other means of maintaining foam stability must be sought.

The paper industry traditionally used water on a profligate scale. In recent decades the industry has responded to increasingly stringent environmental demands by various measures, one of the most cost-effective of which has been to reduce water consumption and consequential discharge. In fact, it has now become received wisdom among paper makers that reduced water consumption and reduced environmental impact go hand in hand. Reflecting this belief, regulatory authorities have increased the pressure upon the paper industry to reduce water discharges. Operation with Zero Liquid Effluent is now widely accepted as being best for the environment. The research reported in this thesis demonstrates that in mills making fine papers, this is not necessarily the case. In such mills, the minimal environment impact may well result from operating with a small, but non-zero, discharge of water, purified before final discharge to a watercourse. The reason lies in the nature of operation in fine paper mills. In such mills, grade changes take place very frequently, often several times each day on each machine. Each grade of fine paper is made from a furnish comprising a unique combination of raw materials, including special chemicals, dyes, and fillers. A portion of these materials fails to be retained during sheet forming. This portion remains in the backwater, in dissolved or suspended form, and is ultimately returned to the forming section. Backwater from one grade of paper cannot be used for another grade, because doing so would result in off-grade paper. During grade changes, therefore, the papermakers purge contaminants from the backwater system, by dumping contaminated backwater and by making off-grade paper, which must also be dumped. Both strategies result in brief shock loads on the environmental protection system.

major research project was undertaken to address the problem of significant losses to drain of process materials in a lightweight paper mill. Current thinking among papermakers is that minimisation oflosses is best achieved by focussing on internal mill efficiencies rather than post-process technologies. Additionally a technologically effective solution to the problem of raw materials losses must also be a cost effective solution. The approach adopted therefore was to apply known principles of paper science to focus on the needs of a specific mill, as identified by comprehensive survey of the mills' operations. Two key areas of mill operations were identified by preliminary investigations as having significant impacts on drain losses at the mill: the control of and influence on product quality of entrained gases and the role of wet end chemistry in determining fibre and filler retention and product quality. Levels of entrained air in the papermaking stock were found to be in the range 0.2 to over 1.0% by volume. These levels were controlled by large volumes of fresh water addition and by chemical defoamers. Entrained air levels in excess of O.2% were found to have a deleterious effect on paper formation and caused unacceptable cross machine variations in air permeability, a key parameter for this grade of paper. An optimum level of chemical defoamer addition was found which controlled the levels of entrained gases and brought about significant improvements in formation, tensile strength and CD air permeability variation. Air permeability variation was reduced by 21% and bonding strength increased by 5%. This optimum level also removed the necessity for the addition of large volumes of fresh water to control stock temperatures.

This thesis contains a comprehensive investigation into the interactions of combinations of cationic polyacrylamide polymers of varying charge density and molecular weight and six microparticles of varying size, shape and type, with two papermaking fillers (one kaolin and one precipitated calcium carbonate). The interaction and adsorption behaviour of the polymers with the microparticles and fillers were determined by back polyelectrolyte titration using a streaming current detector to determine the end point. The flocculation of these fillers with the polymers and combinations of the polymers and microparticles was monitored in real time with a Photometric Dispersion Analyser. Modification of the commercially available machine to allow the study of fibre containing papermaking furnishes has been made and is described. Detailed characterisation of the resultant floes has been undertaken by Coulter Laser Sizer and photographic means. The drainage behaviour of the floes and the flocculated furnish has been investigated and the filler retention levels measured. Mechanisms to describe the behaviour of these microparticle retention systems have been proposed.

This thesis presents an experimental investigation into the relationship between the in-plane structure of paper and its optical uniformity. Analysis has been carried out on a range of different papers, including laboratory formed handsheets, pilot machine made papers and commercial grades. Techniques have been developed to allow light transmission and radiographic images of the same sample area to be compared zone by zone over a range of scales. For a given sample the coefficient of variation of local transmittance determined over a range of scales, has a linear relationship with the coefficient of variation of local grammage and this passes through the origin. The gradient of this relationship is almost always less than one. This linear relationship presents the possibility for mass distribution statistics at all scales of interest to be determined from measurements of local grammage and transmittance at one scale. It is shown that a distribution of local grammage values may be associated with a given transmittance value and that this is well approximated by the Gaussian distribution and as such may be characterised by its mean and coefficient of variation. A technique that allows local grammage data to be stochastically recovered from light transmission data using knowledge of the characterising statistics of these distributions is presented. The theory of Kubelka and Munk is applied to samples in an attempt to provide the basis for a calibration based upon the optical properties of the sheet. The global average specific light scattering and absorption coefficients of many samples are considered with respect to physical sheet properties, to investigate what governs the nature of the linear relationship between the coefficient of variation of local transmittance with that of local grammage over a range of scales of inspection. The potential for this information to be utilised in simulation studies to determine information about local transmittance distributions is demonstrated. The effects of global apparent density on the optical properties of samples are considered. It is shown that the distributions of local transmittance for samples with a given apparent density fall within transmission curves determined from the Kubelka-Munk theory for sheets which are considerably more or less dense. Theoretical curves fitted heuristically to such transmittance and grammage data allow the range of local densities for the sample to be inferred.

The work presented studies the cellulolytic system of <I>Trichoderma koningii</I> with particular reference to its ability to produce "short fibres" in the early stages of cellulose degradation. The culture filtrate of this organism was shown to produce short fibres from both filter paper (Whatman No.1) and cotton (Texas, non-dewaxed). The optimum conditions for production were identified and an assay system developed to measure this activity. Assay using filter paper was rapid and sensitive in determining short fibre producing activity, all results were subsequently confirmed on the more resistant substrate (cotton). The cellulase system was separated using an ion exchanger with a non-carbohydrate matrix and affinity chromatography on cellulose. Initial separation on ion exchange yielded the main cellobiohydrolase (CBH 1). Another fraction from this column separated on cellulose columns gave purified fractions of β-glucosidase, CM-cellulase and the short fibres forming activity (D2Cc). Only this latter fraction produced short fibres and synergised with CM-cellulase and β-glucosidase to increase short fibre production. Short fibres produced by D2Cc were more susceptible to subsequent hydrolysis by culture filtrate or CBH 1, degraded (bacterial) cellulose showed no physical changes on action of D2Cc but subsequent hydrolysis by CBH 1 or culture filtrate was increased. The main product of D2Cc was cellobiose but some cellotriose was detected from filter paper. D2Cc was inactive against cellobiose and cellotriose, both were potent inhibitors of D2Cc activity. Cellobiose was also an inhibitor of CBH 1 but cellotriose was not. D2Cc was shown to reduce the DP of bacterial cellulose. D2Cc and CBH 1 synergised in hydrolysing degraded cellulose, filter paper and cotton. The suggested role for this enzyme component is that it produces short fibres in concert with CM-cellulase which are then attacked by CBH 1 to produce cellobiose which is utilized by the organism.